The present invention is directed generally to aircraft flight instruments, and more particularly to a display system for use in landing an aircraft under adverse weather conditions.
Various types of flight director systems are presently in use for assisting a pilot in landing in marginal weather conditions. Basically, these systems utilize movable bars, flags or other types of command symbols superimposed on the aircraft artifical horizontal to command the pilot to execute roll and pitch maneuvers required to direct the aircraft to the runway threshold. In the case of an instrument landing system (ILS) runway, the aircraft is first directed by the flight director system to intercept the localizer and glide slope beams, and once these have been intercepted, to perform necessary left and right and up and down maneuvers to follow the beams to the runway.
One drawback of existing flight director systems is that the pilot is relegated to blindly follow the flight director commands, and is not presented with information from which he can readily ascertain the relative position of his aircraft with respect to the runway. Such information is readily ascertained by the pilot during visual approaches, which allows these approaches to be flown with a degree of precision heretofore unobtainable with flight director displays. The inability to be able to independently verify position not only may lead to considerable anxiety on the part of the pilot in low weather minimums, but also may prevent the pilot from modifying the flight director commands to obtain a more confortable and efficient descent profile when abnormal conditions exist, such as unusual winds or intercept angles.
The present invention provides the pilot with a pictorial display which presents the landing runway and projected flight path of the aircraft in true visual perspective as if viewed from the aircraft position whereby the pilot can make approaches with a degree of precision approaching that of visual conditions.